Asts-less block redundant electrical topology with variable ups walk-ins

ABSTRACT

Systems and method for the distribution of data center power are disclosed. In one embodiment, the system includes a reserve power system comprising a switchboard, reserve UPS, and generator; and a primary power system, the primary power system comprising a primary UPS coupled to a primary power source via a primary input, a critical load via a primary output, and the reserve power system via an automatic bypass input. The primary power system may be configured to supply power from a utility to the critical load, detect an outage of the utility, supply power to the critical load using a stored energy device in response to detecting an outage of the utility, monitor the capacity of the stored energy device, transmit an on bypass request to the reserve power system transfer the critical load to the reserve power system upon determining that the capacity of the stored energy device has reached a pre-determined threshold, determine that the reserve power system is able to support the critical load and transfer the critical load to the reserve power system if the reserve system is able to support the critical load.

COPYRIGHT NOTICE

This application includes material that may be subject to copyrightprotection. The copyright owner has no objection to the facsimilereproduction by anyone of the patent disclosure, as it appears in thePatent and Trademark Office files or records, but otherwise reserves allcopyright rights whatsoever

BACKGROUND

The present disclosure relates to power distribution networks, and morespecifically to a system and method for providing block redundant backuppower without utilizing an automatic static transfer switch.

As the size of data centers continues to increase exponentially, thenumber of devices required to support data center operations equallycontinues to increase. In order to support the growing number of devices(e.g., servers) required by data centers, operators are continuallyfaced with managing the costs of efficiently powering these datacenters. In context, power and cooling expenses can easily account forthirty percent or more of operating expenditures for most large datacenters. Further, the capital expenditure by data center operators isequally increased due to the power and cooling hardware requirements forsupporting additional data center devices such as servers.

A majority of data centers employ numerous pieces of hardware toimplement power distribution networks. One of these pieces of hardwareis an automatic static transfer switch (ASTS). An ASTS is designed toautomatically switch between utility power and backup power (e.g.,generator power) in the event of a power utility outage. ASTS devicesare generally created by using power semiconductors (e.g., thyristors)to enable fast switching between power sources, generally requiring aquarter of a power cycle to switch between sources.

ASTS devices are generally used to switch the input of anuninterruptible power supply (UPS) between utility power and backuppower (e.g., generator power). In current data center deployments, ASTSdevices are necessary if the data center uses flywheel-based UPSdevices. Flywheel-based UPS devices provide numerous benefits overbattery-based UPS devices including reduced maintenance, lower costs,and lower environmental impact. However, these benefits come at the costof reduced duration of power output from the flywheel(s). That is,flywheel-based UPS devices provide a significantly duration of storedpower output. Thus, when using flywheel-based UPS devices, data centerscommonly are required to use ASTS devices to provide rapid switchingbetween power sources in order to compensate for the shorter duration ofstored power output.

While ASTS devices allow for the continuous supply of power and enablerapid switching between power supplies, the advantages provided by ASTSdevices suffer from numerous deficiencies and tradeoffs.

First, ASTS devices are highly complicated electrical devices and datacenters must add additional cable terminations and breakers in order tosupport the ASTS devices. Second, the ASTS devices introduce additionalpoints of failure in the overall electrical topology of a data centerand are prone to malfunctions. Adding additional points of failureincreases the chances of an outage due to faults in the ASTS devicesand, correspondingly, increases the chances of major revenue losses fordata center operators. Third, ASTS devices are expensive devices whichdirectly increase the capital expenditures of data centers andadditionally increase operating expenditure due to ongoing maintenance.

Thus, there exists a problem in the current state of the art: how toreduce the costs and risks associated with ASTS devices whilemaintaining continuous uptime of a power distribution networks.

BRIEF SUMMARY

To remedy these deficiencies, systems and methods are disclosed hereinwhich allow data centers to reap the benefits of, for example,flywheel-based UPS devices while avoiding the costs and risks associatedwith ASTS devices that are currently required in data center powerdistribution networks. To eliminate the need for ASTS devices, thesystems and methods utilize the automatic bypass input of UPS devices toquickly provide reserve power. By using an automatic bypass input of aUPS device, the systems and methods allow data center operators toremove complicated switching equipment, such as ASTS devices, and relyon the UPS itself to draw on power provided by a reserve power system.Additionally, the systems and method provide for management of thereserve power system, thus enabling the UPS devices to switch to reservepower quickly while ensuring that the reserve system is not overloaded.

In one embodiment, a system includes a reserve power system comprising aswitchboard, reserve UPS, and generator; and a primary power system, theprimary power system comprising a primary UPS coupled to a primary powersource via a primary input, a critical load via a primary output, andthe reserve power system via an automatic bypass input. The primarypower system may be configured to supply power from a utility to thecritical load, detect an outage of the utility, supply power to thecritical load using a stored energy device in response to detecting anoutage of the utility, monitor the capacity of the stored energy device,transmit an on bypass request to the reserve power system transfer thecritical load to the reserve power system upon determining that thecapacity of the stored energy device has reached a pre-determinedthreshold, determine that the reserve power system is able to supportthe critical load, and transfer the critical load to the reserve powersystem if the reserve system is able to support the critical load.

In another embodiment, a method comprises supplying power from a utilityto a critical load via a primary power system comprising a primary UPScoupled to a primary power source via a primary input, a critical loadvia a primary output, and a reserve power system via an automatic bypassinput; detecting an outage of the utility by monitoring the powerreceived via a primary input of the primary UPS; supplying power to thecritical load using a stored energy device in response to detecting anoutage of the utility; monitoring the capacity of the stored energydevice while supplying power to the critical load using a stored energydevice; transmitting an on bypass request to the reserve power systemupon determining that the capacity of the stored energy device hasreached a pre-determined threshold, wherein the on bypass request istransmitted from the primary UPS to a switchboard of the reserve powersystem; determining that the reserve power system is able to support thecritical load; and transferring the critical load to the reserve powersystem if the reserve system is able to support the critical load,wherein transferring the critical load to the reserve power systemcomprises coupling the critical load to the switchboard via an automaticbypass input of the primary UPS.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features, and advantages of thedisclosure will be apparent from the following description ofembodiments as illustrated in the accompanying drawings, in whichreference characters refer to the same parts throughout the variousviews. The drawings are not necessarily to scale, emphasis instead beingplaced upon illustrating principles of the disclosure.

FIG. 1 is a block diagram of a power distribution system according tosome embodiments of the disclosure.

FIG. 2 is a block diagram of a power distribution system illustratingthe flow of power according to some embodiments of the disclosure.

FIG. 3 is a flow diagram illustrating a method for providing generatorpower in a power distribution system according to some embodiments ofthe disclosure.

FIG. 4 is a flow diagram illustrating a method for providing reservepower in a power distribution system according to some embodiments ofthe disclosure.

FIG. 5 is a flow diagram illustrating a method for prohibiting thetransfer of a load to a reserve power system according to someembodiments of the disclosure.

FIG. 6 is a block diagram of a load monitoring system according to someembodiments of the disclosure.

DETAILED DESCRIPTION

The present disclosure will now be described more fully hereinafter withreference to the accompanying drawings, which form a part hereof, andwhich show, by way of illustration, certain example embodiments. Subjectmatter may, however, be embodied in a variety of different forms and,therefore, covered or claimed subject matter is intended to be construedas not being limited to any example embodiments set forth herein;example embodiments are provided merely to be illustrative. Likewise, areasonably broad scope for claimed or covered subject matter isintended. Among other things, for example, subject matter may beembodied as methods, devices, components, or systems. Accordingly,embodiments may, for example, take the form of hardware, software,firmware or any combination thereof (other than software per se). Thefollowing detailed description is, therefore, not intended to be takenin a limiting sense.

Throughout the specification and claims, terms may have nuanced meaningssuggested or implied in context beyond an explicitly stated meaning.Likewise, the phrase “in one embodiment” as used herein does notnecessarily refer to the same embodiment and the phrase “in anotherembodiment” as used herein does not necessarily refer to a differentembodiment. It is intended, for example, that claimed subject matterinclude combinations of example embodiments in whole or in part.

In general, terminology may be understood at least in part from usage incontext. For example, terms, such as “and”, “or”, or “and/or,” as usedherein may include a variety of meanings that may depend at least inpart upon the context in which such terms are used. Typically, “or” ifused to associate a list, such as A, B or C, is intended to mean A, B,and C, here used in the inclusive sense, as well as A, B or C, here usedin the exclusive sense. In addition, the term “one or more” as usedherein, depending at least in part upon context, may be used to describeany feature, structure, or characteristic in a singular sense or may beused to describe combinations of features, structures or characteristicsin a plural sense. Similarly, terms, such as “a,” “an,” or “the,” again,may be understood to convey a singular usage or to convey a pluralusage, depending at least in part upon context. In addition, the term“based on” may be understood as not necessarily intended to convey anexclusive set of factors and may, instead, allow for existence ofadditional factors not necessarily expressly described, again, dependingat least in part on context.

The present disclosure is described below with reference to blockdiagrams and operational illustrations of methods and devices. It isunderstood that each block of the block diagrams or operationalillustrations, and combinations of blocks in the block diagrams oroperational illustrations, can be implemented by means of analog ordigital hardware and computer program instructions. These computerprogram instructions can be provided to a processor of a general purposecomputer to alter its function as detailed herein, a special purposecomputer, ASIC, or other programmable data processing apparatus, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, implement thefunctions/acts specified in the block diagrams or operational block orblocks. In some alternate implementations, the functions/acts noted inthe blocks can occur out of the order noted in the operationalillustrations. For example, two blocks shown in succession can in factbe executed substantially concurrently or the blocks can sometimes beexecuted in the reverse order, depending upon the functionality/actsinvolved.

These computer program instructions can be provided to a processor of: ageneral purpose computer to alter its function to a special purpose; aspecial purpose computer; ASIC; or other programmable digital dataprocessing apparatus, such that the instructions, which execute via theprocessor of the computer or other programmable data processingapparatus, implement the functions/acts specified in the block diagramsor operational block or blocks, thereby transforming their functionalityin accordance with embodiments herein.

For the purposes of this disclosure a computer readable medium (orcomputer-readable storage medium/media) stores computer data, which datacan include computer program code (or computer-executable instructions)that is executable by a computer, in machine readable form. By way ofexample, and not limitation, a computer readable medium may comprisecomputer readable storage media, for tangible or fixed storage of data,or communication media for transient interpretation of code-containingsignals. Computer readable storage media, as used herein, refers tophysical or tangible storage (as opposed to signals) and includeswithout limitation volatile and non-volatile, removable andnon-removable media implemented in any method or technology for thetangible storage of information such as computer-readable instructions,data structures, program modules or other data. Computer readablestorage media includes, but is not limited to, RAM, ROM, EPROM, EEPROM,flash memory or other solid state memory technology, CD-ROM, DVD, orother optical storage, magnetic cassettes, magnetic tape, magnetic diskstorage or other magnetic storage devices, or any other physical ormaterial medium which can be used to tangibly store the desiredinformation or data or instructions and which can be accessed by acomputer or processor.

FIG. 1 is a block diagram of a power distribution system according tosome embodiments of the invention.

As illustrated in FIG. 1, a utility 102 provides power to a criticalloads 114 via a primary power system including transformer 104,generator 106, automatic transfer switch (ATS) 108, switchboard 110, andprimary UPS 112. In one embodiment, utility 102 comprises a publicutility, such as a power plant or other power generation source, whichprovides power via one more substations.

Critical loads 114 may include a variety of data center hardware such asservers or other data processing devices. For example, critical loads114 may include one or more servers (e.g., an email server, a proxyserver, a domain name system (DNS) server, a file server, an applicationserver, a firewall, a virtual private network (VPN) gateway, anintrusion detection system), networking equipment (e.g., a router, arepeater, a switch, a hub), mainframe computer, and storage devices. Astorage device includes a random access memory (RAM), a read-only memory(ROM), or a combination thereof. Examples of a storage device include aflash memory, a redundant array of independent disks, a hard disk, or acombination thereof

In some embodiments, a critical load may include a plurality of serversarranged on one or more racks. Each server may be coupled to a unitdistribution panel (UDP) which supplies power to the individual servers.In some embodiments, each critical load may include one or more UDP s.In one embodiment, a UDP may be coupled to primary UPS 112 and maydistribute a single current from the primary UPS 112 to multiple devicesincluded in the critical load.

In normal operation, utility 102 provides alternating current (AC) powerto transformer 104. Transformer 104 may comprise a step down transformerutilized to step down input voltage from utility 102 to a pre-definedvoltage level required by ATS 108. In some embodiments, transformer 104may comprise multiple transformers.

ATS 108 receives stepped-down voltage from transformer 104 and, innormal operation, distributes power to switchboard 110.

In one embodiment, ATS 108 may comprise any suitable automatic transferswitch capable of switching between utility power and power receivedfrom a backup power source such as generator 106. In some embodiments,the ATS 108 may be configured to start generator 106. That is, in theevent of a loss of power from utility 102, the ATS 108 may be configuredto communicate with generator 106 in order to start the operation ofgenerator 106. ATS 108 may issue a command to start a generator 106 bymonitoring voltage levels received from transformer 104. Alternatively,ATS 108 may be configured to relay a command to start a generator 106from another device, such as primary UPS 112 or an external networkdevice.

Notably, ATS 108 may comprise any non-static transfer switch. Incontrast to current power distribution networks employed by datacenters, the system does not require the use of an ASTS in place of ATS108 in order to quickly switch to backup power. Specifically, asdiscussed in more detail herein, the use of a lower cost and morereliable ATS 108 is enabled due to the coupling of UPS 112 and reservepower system 116 via an automatic bypass input. That is, the use ofreserve power system 116 coupled to an automatic bypass input of UPS 112enables reliable switching to backup power without the use of a highlycomplicated ASTS device used in place of ATS 108.

As illustrated in FIG. 1, ATS 108 provides power to switchboard 110. Inthe illustrated embodiment, switchboard 110 divides the current receivedfrom ATS 108 and distributes the current to one or more primary UPSdevices. Although illustrated as a single device, the data centerillustrated in FIG. 1 may house multiple primary UPS 112 devices.Reference is made in FIG. 1 to a single primary UPS 112 and thedescription thereof applies equally to additional primary UPS devicesdeployed within a data center.

Primary UPS 112 receives power from switchboard 110. In one embodiment,primary UPS 112 may include a plurality of electrical inputs including aprimary input, automatic bypass input, and maintenance bypass input.Additionally, primary UPS 112 may include a plurality of electricaloutputs including a primary output. In some embodiments, primary UPS 112may be a line-interactive UPS. In this embodiment, the primary UPS 112may be configured to control the frequency synchronization of the outputwith an automatic bypass input received from the reserve power system116.

In normal operation, primary UPS 112 receives power from switchboard 110via a primary electrical input present on the primary UPS 112. During anoutage, primary UPS 112 may receive power from switchboard 126 via anautomatic bypass input. In the illustrated embodiment, primary UPS 112is configured to toggle between a primary input and an automatic bypassinput upon the detection of a triggering condition. In one embodiment,primary UPS 112 may be configured to automatically “fail” to anautomatic bypass input upon the detection of certain events such aspower outages or device failures.

As discussed previously, by coupling primary UPS 112 to switchboard 126,the automatic triggering of ATS 108 may be prevented. Specifically, upondetecting an outage, in previous systems, a primary UPS would transmit asignal to an ASTS device causing a switch to backup power. In theillustrated system however, primary UPS 112 transmits an on bypasssignal to switchboard 126 instead, thus obviating the need for an ASTSdevice in order to provide reserve power.

In one embodiment, primary UPS 112 may switch between a primary inputand an automatic bypass input utilizing an electrically operated circuitbreaker coupled to the primary input and automatic bypass input. In thisembodiment, electrically operated circuit breakers may be controlled bya bypass controller present within the UPS 112.

In one embodiment, primary UPS 112 may be configured to monitor theinput voltage level received from utility 102. Upon detecting an outageor fluctuation in the voltage or current level from utility 102, theprimary UPS 112 may be configured to automatically switch to theautomatic bypass input. In alternative embodiments, primary UPS 112 maybe further configured to switch to the automatic bypass input ifadditional conditions have been met.

For example, primary UPS 112 may be configured to determine whethergenerator 106 has been fully started following the detection of autility 102 outage. Commonly, generators may be slow to start followingthe detection of a power outage. In this scenario, primary UPS 112 maymonitor generator 106 by monitoring the voltage or current output ofgenerator 106.

Prior to switching to an automatic bypass, and immediately afterdetecting a utility 102 outage, primary UPS 112 may be configured toprovide power via primary output using a stored energy device. In oneembodiment, the stored energy device may comprise a battery-based storedenergy device. In alternative embodiments, stored energy device maycomprise a flywheel-based stored energy device.

Notably, however, primary UPS 112 may only be capable of providing powerfor a limited duration when using a stored energy device. For example,many flywheel-based UPS devices provide power output for onlyapproximately ten seconds. Thus, primary UPS 112 may monitor the outputof the stored power (e.g., flywheel output) in order to determine whenthe stored capacity nears a pre-determined cutoff threshold (e.g., 7%capacity remaining). Upon reaching this threshold, primary UPS 112 mayagain determine whether the output voltage of generator 106 has reachedan acceptable level. If it is determined that generator 106 has not metthe required output, primary UPS 112 may be configured to generate an“on bypass” signal. In the illustrated embodiment, primary UPS 112 maytransmit the on bypass signal to switchboard 126 rather than switchboard110. Thus, by preventing the transmission of the on bypass signal toswitchboard 110, the system prevents the automatic starting of generator106. That is, the primary UPS 112 may be configured to attempt toutilize reserve power system 116 rather than generator 106.

As discussed previously, primary UPS 112 may utilize an automatic bypassinput source when determining that an outage is ongoing and thatgenerator 106 has not yet reached a required power output level. Asillustrated in FIG. 1, the automatic bypass input of primary UPS 112 maybe connected to reserve power system 116.

Reserve power system 116 may include similar components as the primarypower system discussed previously. Specifically, transformer 118,generator 120, and ATS 122 may be similarly constructed and providesimilar functionality as transformer 104, generator 106, and ATS 108,respectively. Thus, the descriptions of transformer 104, generator 106,and ATS 108 are incorporated herein by reference with respect totransformer 118, generator 120, and ATS 122.

As illustrated in FIG. 1, reserve power system 116 includes a reserveUPS 124 that is connected to the output of ATS 122 and thus receivespower from utility 102 (via transformer 118) or generator 120. ReserveUPS 124 provides power output to switchboard 126, which in turn dividesthe received current and distributes the current to the automatic bypassinput of primary UPS 112. In the illustrated embodiment, a data centermay include only a single reserve power system 116, while containingmany primary UPS devices. Thus, the reserve power system 116 utilizes aswitchboard to determine which primary UPS devices have requested powerfrom the reserve power system 116 and which primary UPS devices arecurrently drawing power from reserve power system 116.

In alternative embodiments, reserve power system 116 may be connected toadditional reserve power systems via reserve UPS 124. Specifically,reserve UPS 124 may also include an automatic bypass input similar toprimary UPS 112. The automatic bypass input of reserve UPS 124 may thenbe connected to a second reserve power system containing the samecomponents as reserve power system 116. In alternative embodiments, thesystem 100 may include numerous reserve power systems connected viabypass inputs of their respective UPS devices, thus forming a “daisychained” reserve power system.

In the illustrated embodiment, the reserve power system 116 may furtherinclude a load monitoring system 128. In one embodiment, load monitoringsystem 128 may comprise hardware and/or software configured to monitorthe various components (e.g., reserve UPS 124 and switchboard 126) ofthe reserve power system 116. In one embodiment, load monitoring system128 may comprise a device as illustrated in more detail with respect toFIG. 6. In one embodiment, load monitoring system 128 monitors thereserve power system 116 to determine the power drawn from reservesystem 116. For example, load monitoring system 128 may monitor reserveUPS 124 to determine the percentage of the reserve UPS 124 energycapacity currently used by system. In one embodiment, the loadmonitoring system 128 may be further configured to prevent a primary UPS112 from drawing power from reserve power system 116. For example, loadmonitoring system 128 may receive a request to transfer critical loads114 to reserve power system 116. The load monitoring system 128 may thendetermine the usage of the reserve power system 116 upon receiving sucha request. If load monitoring system 128 determines that the reservepower system 116 is currently operating under a pre-determined operatingthreshold, the load monitoring system 128 may allow primary UPS 112 totransfer to reserve power system 116. Alternatively, if load monitoringsystem 128 determines that reserve power system 116 is operating at orabove the pre-determined operating threshold, load monitoring system 128may prevent primary UPS 112 from transferring the critical loads 114 tothe reserve power system 116. A method for inhibiting transfers of aprimary UPS 112 is described more fully with respect to FIG. 5.

FIG. 2 is a block diagram of a power distribution system illustratingthe flow of power according to some embodiments of the invention. FIG. 2illustrates the flow of power in three scenarios: normal input (210),reserve input (212), and automatic bypass input (214)

As illustrated in FIG. 2, during a normal mode of operation, power isreceived from primary power source 202 and supplied via line 210 a toUPS 204 a at a primary input. As discussed previously, primary powersource 202 may comprise a utility or backup power source (e.g., a dieselgenerator). In one embodiment, UPS 204 a utilizes the received power torecharge any stored energy devices. UPS 204 a subsequently providesoutput power to unit distribution panel (UDP) 206 a via line 210 b.

Additionally illustrated in FIG. 2 is the operation of a powerdistribution system during a “reserve” mode of operation. In this mode,UPS 204 b does not receive power from primary power source 202 asindicated by “dead” line 216 a. As discussed previously, UPS 204 b mayenter a monitoring stage upon detecting an outage of utility power.Additionally, UPS 204 b may enter a “reserve” mode upon determining thatgenerator power is not available and the power level of any storedenergy reserves has reached a critical level. Upon entering a reservemode, UPS 204 b switches its input to an automatic bypass input andreceives power from reserve source 208 via line 212 a. In this mode ofoperation, UPS 204 b may continue to operate as if receiving power fromprimary power source 202. That is, UPS 204 b may continue to rechargeany internal energy storage devices and may provide power to UDP 206 bvia line 212 b.

As discussed previously, UPS 204 b may operate in reserve mode until aprimary power source 202 is available. For instance, UPS 204 b maydetermine that a generator has reached the required voltage level andmay re-enter a normal mode as discussed previously. Alternatively, UPS204 b may determine that a utility outage has ceased prior to agenerator reaching the required voltage level and may thus return to anormal mode using utility power.

Additionally illustrated in FIG. 2 is the operation of a powerdistribution system during a “bypass” mode of operation. In a bypassmode of operation, UDP 206 c does not receive power from the UPS 204 cand instead receives power directly from reserve source 208 via line214.

The system may enter a bypass mode in a variety of ways. In oneembodiment, the system may enter a bypass mode upon detecting a fault inUPS 204 c that prevents UPS 204 c from supplying power to the UDP 206 c,regardless of source. Alternatively, the system may enter a bypass modewhen maintenance is being performed on UPS 204 c. In this embodiment, atechnician may manually place the system in bypass mode in order toperform maintenance or replace UPS 204 c.

As can be seen in FIG. 2, the use of an automatic bypass input of UPS204 a-c allows a data center to avoid the use of additional externalswitching equipment such as an ASTS. Specifically, as illustrated inconnection with UPS 204 b, the system enables a UPS to automaticallyfail to a reserve power system using only the UPS device itself.Additionally, since the reserve source is coupled to, for example, UDP206 c, external switching equipment is not needed even if a given UPS,e.g., UPS 204 c, fails completely.

FIG. 3 is a flow diagram illustrating a method for providing generatorpower in a power distribution system according to some embodiments ofthe disclosure.

As illustrated in FIG. 3, the method 300 provides utility power, step302. In one embodiment, utility power may comprise power received at adata center from a public utility via one more substations. In oneembodiment, the method 300 may provide utility power to a plurality ofcritical loads via a primary UPS device and other electrical hardware asdiscussed more fully with respect to FIG. 1. That is, utility power maybe received by the method 300 from a utility, stepped down using atransformer, and routed to a UPS device using an ATS. In alternativeembodiments, step 302 may additionally include recharging a storedenergy device present within the primary UPS. In alternativeembodiments, the method 300 may monitor the power received from autility in addition to monitoring power usage within the data center.

The method 300 continues providing utility power until an outage isdetected, step 304. In one embodiment, detecting an outage may comprisemonitoring the input voltage of a primary UPS device and determiningthat the source voltage level falls below a minimum threshold.Alternatively, or in conjunction with the foregoing, detecting an outagemay comprise detecting an under or over voltage or an under or overfrequency.

Upon detecting that an outage of a utility has occurred, the method 300begins providing stored power, step 306. In one embodiment, providingstored power may comprise providing power from a primary UPS usingstored energy devices present within the primary UPS. In one embodiment,the stored energy device may comprise one or more batteries connected toor contained within the primary UPS. In alternative embodiments, thestored energy device may comprise a flywheel connected to or containedwithin the primary UPS. In some embodiments, providing stored power maybe performed automatically upon detecting a utility outage.

In the illustrated embodiment, supplying stored power enables thecontinuous operation of critical loads during utility outages orfluctuations while the primary UPS awaits a backup power source such asa diesel generator. However, proactively starting a backup generator forevery potential outage may result in strain on the generator as well asunnecessary generator starts. Thus, in order to prevent unnecessarygenerator starts, the method 300 runs a time delay engine start timer(TDES), step 308. In some embodiments, a TDES timer may comprise a timerhaving a pre-configured duration that prevents the method 300 fromattempting to issue a start generator command (step 312). For example, atime delay engine start may be set to one second. If so, the method 300may delay starting a generator for a period of one second afterdetermining that an outage has occurred. Upon the expiration of the timedelay engine start timer, step 308, the method 300 may start thegenerator. However, if after one second, the method 300 determines thatthe utility has restored power, the method 300 may end and continue toutilize utility power as the input of a primary UPS. Notably, the use ofa time delay engine start timer prevents unnecessary generator startsfor utility outages of shorter durations.

In step 312, the method 300 issues a start generator command. In oneembodiment, issuing a start generator command may comprise closing astart signal contact. In the illustrated embodiment, after issuing astart generator command, the method 300 may additionally run a timedelay normal to emergency (TDNE) timer, step 314. In one embodiment, theTDNE timer may comprise a timer having a pre-configured delay periodallowed after the generator has started and both the voltage andfrequency from the generator are deemed acceptable to the monitoringrelays. If the utility is restored or an external signal that caused thestart of the generator is restored before this delay expires, notransfer may occur. Once this delay expires the transfer to generatormay be committed.

The method 300 continues to check to determine if the TDNE timer hasexpired, step 316. After the expiration of the TDNE timer, the method300 determines whether a backup generator is currently available, step318. In one embodiment, determining whether a generator is availablecomprises determining whether the output voltage of an externalgenerator meets a minimum required voltage level.

If the method 300 determines that a generator is available (e.g., thegenerator is outputting a voltage level above a required level), themethod 300 may switch power sources to the generator and thus providegenerator power to the critical loads, step 320. Alternatively, if themethod 300 determines that a backup generator is not currentlyavailable, the method 300 may attempt to transfer the critical load to abackup power system as discussed more fully with respect to FIG. 4.

FIG. 4 illustrates a method for providing reserve power in a powerdistribution system according to some embodiments of the disclosure.

As discussed previously, the method 400 illustrated in FIG. 4 may beperformed if it is determined that an external generator is notavailable. In some embodiments, an external generator may take asignificant amount of time to start and thus may not be available toprovide sufficient power to ensure uninterrupted operation of a criticalload. In some embodiments, a primary UPS utilizing a flywheel-basedstored energy device may only supply a limited duration of internalpower, a duration shorter than the time required to start a generator.

In step 402, the method 400 provides stored power from a stored energydevice. In one embodiment, the stored energy device may comprise one ormore batteries connected to or contained within the UPS. In alternativeembodiments, the stored energy device may comprise one or more flywheelsconnected to or contained within the primary UPS.

In step 404, the method 400 monitors the stored power consumption of thestored energy device. In one embodiment, monitoring the stored powerconsumption may comprise monitoring the output voltage of the primaryUPS device to determine if the stored power of the stored energy deviceis low. In one embodiment, monitoring a stored power device may comprisemonitoring the capacity of the stored power device. In alternativeembodiments, the method 400 may utilize a predetermined threshold fordetermining when the stored power device is low. For example, the method400 may determine when the capacity of the stored power device is atseven percent. When the capacity of the stored power device approachesthis limit, the method 400 may determine that the capacity of storedpower device has reached the minimum acceptable limit, step 406. Untilreaching that point, the method 400 may continue to supply power to acritical load in step 402.

Upon determining that the capacity of the stored power device hasreached a predefined limit, the method 400 may transmit an “on bypass”signal or request to a reserve power system, step 408. The on bypasssignal may be sent from a primary UPS to a reserve power systemswitchboard. In one embodiment, the on bypass signal alerts the reservepower system that the primary UPS is attempting to transfer its criticalload to the reserve power system. As discussed previously, by utilizingan automatic bypass input of the UPS that is coupled to a reserve systemswitchboard, the method 400 avoids immediately transmitting an on bypasssignal to a transfer switch, thus obviating the need for an ASTS deviceto provide backup power to UPS device. In one embodiment, the method 400may be configured to automatically “fail” to an automatic bypass inputupon the detection of certain events such as power outages or devicefailures.

After transmitting the on bypass request, the method 400 may determineif a global inhibit signal is enabled, step 410. In the illustratedembodiment, a global inhibit signal may be issued by a reserve powersystem and may prevent the primary UPS devices from transferringcritical loads to the reserve power system when the reserve power systemis unable to support additional critical loads. Issuance of a globalinhibit signal is discussed more fully with respect to FIG. 5 and isincorporated herein by reference.

If the method 400 determines that a global inhibit signal has beenenabled, the method 400 may wait for a primary power source to becomeavailable, step 418. In one embodiment, a primary power source maycomprise a generator or utility power. Upon determining that a primarypower source is available, the method 400 may then transfer a criticalload to the primary power source as a step load, step 420.

Alternatively, if the method 400 determines that a global inhibit signalhas not been enabled, the method 400 may transfer the critical load tothe reserve power system, step 412. In one embodiment, transferring acritical load to a reserve power system may comprise switching the inputline of a primary UPS device from utility power to the output of areserve power system.

In some embodiments, the method 400 may continue to provide power to acritical load using reserve power system until utility power has beenrestored, step 414. Alternatively, the method 400 may continue maycontinue to provide power to a critical load using reserve power systemuntil a generator has started. Alternatively, or in conjunction with theforegoing, the method 400 may additionally monitor the reserve powersystem to determine whether the reserve power system meets predeterminedpower threshold levels.

If the method 400 determines that a primary power source has beenrestored, step 414, the method 400 may transfer the critical load backto the primary system, step 416. In one embodiment, determining whethera primary power source has been restored may comprise monitoring theinput voltage received from utility power. Alternatively, or inconjunction with the foregoing, determining whether a primary powersource has been restored may comprise monitoring the input voltagereceived from an external generator.

FIG. 5 illustrates a method for prohibiting the transfer of a load to areserve UPS system according to some embodiments of the invention.

As illustrated in FIG. 5, a method 500 may receive a bypass request froma primary UPS, step 502. In one embodiment, the primary UPS may comprisea primary UPS coupled to a critical load. For example, as illustrated inFIG. 1, a data center may include multiple critical loads, each criticalload representing multiple computing devices (e.g., servers). For eachcritical load, a primary UPS may be placed between the utility powersource and the critical load. The primary UPS monitors the input voltagereceived from the utility and is capable of transferring the criticalload to backup or reserve power as described in connection with FIG. 3.

Upon detecting a loss of power received from a utility, the primary UPSmay transmits an “on bypass” signal using one or more output ports ofthe primary UPS device. In one embodiment, an “on bypass” signal mayindicate to upstream devices that the UPS is attempting to switch fromutility power to an automatic bypass input line. In one embodiment, themethod 500 may transmit an on bypass signal automatically upon thedetection of a triggering event such as a power outage or devicefailure. In current systems, this signal is used to signal an ASTSdevice to switch to generator power. However, in the method 500, the onbypass signal is transmitted to a reserve power system due to thecoupling of the primary UPS to the reserve system via an automaticbypass input.

In one embodiment, the primary UPS may transmit the on bypass request toa reserve power system. In one embodiment, the reserve power system mayinclude a load monitoring system configured to receive the on bypassrequest and enable or disable the transfer of the primary UPS to thereserve power system. As discussed previously, in one embodiment, thereserve power system may include a switchboard configured to receive theon bypass request. The switchboard may be configured to forward the onbypass request to a load monitoring system which manages the number ofloads connected to the reserve power system as discussed below.

In step 504, the method 500 determines if the reserve power system cansupport an additional critical load. In one embodiment, determining ifthe reserve power system can support an additional critical loadcomprises calculating the total load on the reserve UPS and the reserveswitchboard. In one embodiment, upon receiving an on bypass request, themethod 500 may transmit a request to the reserve UPS and reserveswitchboard requesting usage details regarding the reserve UPS andreserve switchboard. In alternative embodiments, the method 500 mayactively monitor current and/or output voltages of the reserve UPS andreserve switchboard in order to determine usage statistics. In oneembodiment, the method 500 may monitor the reserve switchboard only uponfailing to detect the reserve UPS. That is, the method 500 may primarilymonitor the reserve UPS to determine usage of the reserve power systemand may only monitor the switchboard upon failing to calculate the usageof the reserve power system based on the reserve UPS. In alternativeembodiments, determining if the reserve power system can support anadditional critical load comprises determining if the reserve powersystem is currently in a bypass mode.

In the illustrated embodiment, the method 500 may compare the returnedor monitored usage statistics to a pre-determined reserve threshold todetermine whether the reserve system is operating at maximum capacity,step 506.

For example, a data center may specify that a reserve power system canonly operate at 90% of the maximum capacity of the reserve power system.In this example, the method 500 analyzes the usage statistics todetermine if the reserve power system is at or near the maximumcapacity. Alternatively, or in conjunction with the foregoing, themethod 500 may additionally compute an expected usage based on the onbypass request. That is, the method 500 may forecast the percentage ofusage if the on bypass request was granted.

If the method 500 determines that the reserve power system is notoperating at or near maximum capacity, the method 500 allows the loadpowered by the primary power system to be transferred to the reservepower system, step 508. In one embodiment, transferring the load poweredby the primary power system may be performed according to the methoddescribed in connection with FIG. 3 and is not repeated herein for thesake of clarity. As discussed previously, in some embodiments, themethod 500 may only transfer the critical load to the reserve powersystem only upon determining that the reserve power system is capable ofsupporting the critical load without exceeding the maximum capacity ofthe reserve power system. In one embodiment, reserve power system, via areserve switchboard, may transmit an indication to a primary powersystem that the reserve power system can support additional loads. Inone embodiment, the indication may comprise the lack of a global inhibitsignal.

Upon detecting that the reserve power system is operating (or willoperate) at or above a pre-determined maximum capacity, the method 500transmits a global inhibit signal to the primary UPS systems, step 510.In one embodiment, the method 500 may transmit the global inhibit signalto all primary UPS systems coupled to the reserve power system. Inalternative embodiments, the method 500 may only transmit the globalinhibit signal to those primary UPS systems that are not activelydrawing power from the reserve power system. In alternative embodiments,the method 500 may only transmit the global inhibit signal to theprimary UPS that issued the on bypass request.

The global inhibit signal prevents the primary UPS systems that receivethe signal from transferring their critical loads to the reserve powersystem that issued the global inhibit signal. In one embodiment, inresponse to receiving a global inhibit signal, the primary UPS maytransfer its load to an alternative power source. For example, theprimary UPS may transfer its load to an external generator (e.g., adiesel generator). Specifically, upon receiving a global inhibit signal,the primary UPS may wait until a primary power source becomes availableand may transfer the critical load the primary power source as a stepload once the primary power source is available.

FIG. 6 is a block diagram of a load monitoring system according to someembodiments of the disclosure.

Load monitoring system 600 may include many more or less components thanthose shown in FIG. 6. However, the components shown are sufficient todisclose an illustrative embodiment for implementing the presentdisclosure. Load monitoring system 600 may represent, for example, loadmonitoring systems discussed above in relation to FIG. 1.

As shown in FIG. 6, load monitoring system 600 includes a processingunit (CPU) 622 in communication with a mass memory 630 via a bus 624.Load monitoring system 600 also includes a power supply 626, one or morenetwork interfaces 650, an audio interface 652, a display 654, a keypad656, an illuminator 658, an input/output interface 660, and a camera(s)or other optical, thermal or electromagnetic sensors 662. Loadmonitoring system 600 can include one camera/sensor 662, or a pluralityof cameras/sensors 662, as understood by those of skill in the art.

Power supply 626 provides power to load monitoring system 600. Arechargeable or non-rechargeable battery may be used to provide power.The power may also be provided by an external power source, such as anAC adapter or a powered docking cradle that supplements and/or rechargesa battery.

Load monitoring system 600 may optionally communicate with a basestation (not shown), or directly with another computing device. Networkinterface 650 includes circuitry for coupling load monitoring system 600to one or more networks, and is constructed for use with one or morecommunication protocols and technologies. Network interface 650 issometimes known as a transceiver, transceiving device, or networkinterface card (NIC).

Audio interface 652 is arranged to produce and receive audio signalssuch as the sound of a human voice. For example, audio interface 652 maybe coupled to a speaker and microphone (not shown) to enabletelecommunication with others and/or generate an audio acknowledgementfor some action. Display 654 may be a liquid crystal display (LCD), gasplasma, light emitting diode (LED), or any other type of display usedwith a computing device. Display 654 may also include a touch sensitivescreen arranged to receive input from an object such as a stylus or adigit from a human hand.

Keypad 656 may comprise any input device arranged to receive input froma user. For example, keypad 656 may include a push button numeric dial,or a keyboard. Keypad 656 may also include command buttons that areassociated with selecting and sending images. Illuminator 658 mayprovide a status indication and/or provide light. Illuminator 658 mayremain active for specific periods of time or in response to events. Forexample, when illuminator 658 is active, it may backlight the buttons onkeypad 656 and stay on while the load monitoring system is powered.Also, illuminator 658 may backlight these buttons in various patternswhen particular actions are performed, such as dialing another clientdevice. Illuminator 658 may also cause light sources positioned within atransparent or translucent case of the client device to illuminate inresponse to actions.

Load monitoring system 600 also comprises input/output interface 660 forcommunicating with external devices, such as UPS or switchboard devices,or other input or devices not shown in FIG. 6. Input/output interface660 can utilize one or more communication technologies, such as USB,infrared, Bluetooth™, or the like.

Mass memory 630 includes a RAM 632, a ROM 634, and other storage means.Mass memory 630 illustrates another example of computer storage mediafor storage of information such as computer readable instructions, datastructures, program modules or other data. Mass memory 630 stores abasic input/output system (“BIOS”) 640 for controlling low-leveloperation of load monitoring system 600. The mass memory also stores anoperating system 641 for controlling the operation of load monitoringsystem 600. It will be appreciated that this component may include ageneral purpose operating system such as a version of UNIX, or LINUX™,or a specialized client communication operating system such as WindowsClient™ or the Symbian® operating system. The operating system mayinclude, or interface with a Java virtual machine module that enablescontrol of hardware components and/or operating system operations viaJava application programs.

Memory 630 further includes one or more data stores, which can beutilized by load monitoring system 600 to store, among other things,applications 642 and/or other data. For example, data stores may beemployed to store information that describes various capabilities ofload monitoring system 600. The information may then be provided toanother device based on any of a variety of events, including being sentas part of a header during a communication, sent upon request, or thelike. At least a portion of the capability information may also bestored on a disk drive or other storage medium (not shown) within loadmonitoring system 600.

Application 642 may include computer executable instructions which, whenexecuted by load monitoring system 600, enable the transfer of databetween load monitoring system 600 and other devices within a datacenter. For example, monitoring application 645 may enable the controland operation of a UPS or switchboard device. Alternatively, or inconjunction with the foregoing, monitoring application 645 may enablethe transmission or reception of various signals between data centerhardware. In one embodiment, monitoring application 645 may performsteps of the methods illustrated in connection with FIGS. 4 and 5.Specifically, monitoring application 645 may be configured to receive anon bypass request from a UPS device and determine whether a load shouldbe supported by a reserve power system, or whether a global inhibitsignal should be transmitted to a primary power system.

For the purposes of this disclosure a module is a software, hardware, orfirmware (or combinations thereof) system, process or functionality, orcomponent thereof, that performs or facilitates the processes, features,and/or functions described herein (with or without human interaction oraugmentation). A module can include sub-modules. Software components ofa module may be stored on a computer readable medium for execution by aprocessor. Modules may be integral to one or more servers, or be loadedand executed by one or more servers. One or more modules may be groupedinto an engine or an application.

Those skilled in the art will recognize that the methods and systems ofthe present disclosure may be implemented in many manners and as suchare not to be limited by the foregoing exemplary embodiments andexamples. In other words, functional elements being performed by singleor multiple components, in various combinations of hardware and softwareor firmware, and individual functions, may be distributed among softwareapplications at either the client level or server level or both. In thisregard, any number of the features of the different embodimentsdescribed herein may be combined into single or multiple embodiments,and alternate embodiments having fewer than, or more than, all of thefeatures described herein are possible.

Functionality may also be, in whole or in part, distributed amongmultiple components, in manners now known or to become known. Thus,myriad software/hardware/firmware combinations are possible in achievingthe functions, features, interfaces and preferences described herein.Moreover, the scope of the present disclosure covers conventionallyknown manners for carrying out the described features and functions andinterfaces, as well as those variations and modifications that may bemade to the hardware or software or firmware components described hereinas would be understood by those skilled in the art now and hereafter.

Furthermore, the embodiments of methods presented and described asflowcharts in this disclosure are provided by way of example in order toprovide a more complete understanding of the technology. The disclosedmethods are not limited to the operations and logical flow presentedherein. Alternative embodiments are contemplated in which the order ofthe various operations is altered and in which sub-operations describedas being part of a larger operation are performed independently.

While various embodiments have been described for purposes of thisdisclosure, such embodiments should not be deemed to limit the teachingof this disclosure to those embodiments. Various changes andmodifications may be made to the elements and operations described aboveto obtain a result that remains within the scope of the systems andprocesses described in this disclosure.

What is claimed is:
 1. A system for power distribution comprising: areserve power system comprising a switchboard, reserve UPS, andgenerator; and a primary power system, the primary power systemcomprising a primary UPS coupled to a primary power source via a primaryinput, a critical load via a primary output, and the reserve powersystem via an automatic bypass input, wherein the primary power systemis configured to: supply power from a utility to the critical load viathe primary output; detect an outage of the utility by monitoring thepower received via the primary input; supply power to the critical loadusing a stored energy device in response to detecting an outage of theutility; monitor the capacity of the stored energy device whilesupplying power to the critical load using a stored energy device;transmit an on bypass request to the reserve power system upondetermining that the capacity of the stored energy device has reached apre-determined threshold, wherein the on bypass request is transmittedfrom the primary UPS to the switchboard; determine that the reservepower system is able to support the critical load; and transfer thecritical load to the reserve power system if the reserve system is ableto support the critical load.
 2. The system of claim 1 whereindetermining that the reserve power system is able to support thecritical load comprises determining whether the reserve power system hastransmitted a global inhibit signal.
 3. The system of claim 2 whereinthe reserve power system further includes a load monitoring systemconfigured to: receive the on bypass signal from the primary powersystem; determine if the reserve power system can support the criticalload; enable the transfer of the critical load to the reserve powersystem upon determining that the reserve power system can support thecritical load; and transmit the global inhibit signal to the primarypower system upon determining that the reserve power system cannotsupport the critical load, wherein the global inhibit signal preventsthe primary power system from transferring the critical load to thereserve power system.
 4. The system of claim 3 wherein determining ifthe reserve power system can support the critical load comprises:calculating the total load of the reserve power system; determining thatthe reserve power system can support the critical load if the total loadis below a pre-determined reserve threshold; and determining that thereserve power system cannot support the critical load if the total loadis equal to or above a pre-determined reserve threshold;
 5. The systemof claim 4 wherein calculating the total load of the reserve powersystem comprises calculating the load of the reserve UPS.
 6. The systemof claim 3 wherein determining if the reserve power system can supportthe critical load comprises determining whether the reserve power systemis in a bypass mode. The system of claim 3 wherein the primary powersystem is further configured to: receive a global inhibit signal fromthe reserve power system; monitor the availability of the primary powersource; and transfer the critical load to the primary power source as astep load upon determining that primary power source is available. 8.The system of claim 1 wherein the primary power system is furtherconfigured to: monitor a primary power source after transferring thecritical load to the reserve power system; and transfer the criticalload to the primary power source upon determining that primary powersource is available.
 9. The system of claim 1 wherein the reserve UPSincludes an automatic bypass input and wherein the reserve power systemis coupled to an output of a secondary reserve power system via theautomatic bypass input of the reserve UPS.
 10. The system of claim 1wherein the primary power system is further configured to: initiate atime delay engine start timer in response to detecting an outage of theutility; and issue a start generator command in response to determiningthat the time delay engine start timer has expired.
 11. A method forpower distribution, the method comprising: supplying power from autility to a critical load via a primary power system comprising aprimary UPS coupled to a primary power source via a primary input, acritical load via a primary output, and a reserve power system via anautomatic bypass input; detecting an outage of the utility by monitoringthe power received via the primary input of the primary UPS; supplyingpower to the critical load using a stored energy device in response todetecting an outage of the utility; monitoring the capacity of thestored energy device while supplying power to the critical load using astored energy device; transmitting an on bypass request to the reservepower system upon determining that the capacity of the stored energydevice has reached a pre-determined threshold, wherein the on bypassrequest is transmitted from the primary UPS to a switchboard of thereserve power system; determining that the reserve power system is ableto support the critical load; and transferring the critical load to thereserve power system if the reserve system is able to support thecritical load, wherein transferring the critical load to the reservepower system comprises coupling the critical load to the switchboard viaan automatic bypass input of the primary UPS.
 12. The method of claim 11determining that the reserve power system is able to support thecritical load comprises determining whether the reserve power system hastransmitted a global inhibit signal to the primary power system.
 13. Themethod of claim 12 further comprising: receiving the on bypass signalfrom the primary power system; determining if the reserve power systemcan support the critical load; enabling the transfer of the criticalload to the reserve power system upon determining that the reserve powersystem can support the critical load; and transmitting the globalinhibit signal to the primary power system upon determining that thereserve power system cannot support the critical load, wherein theglobal inhibit signal prevents the primary power system fromtransferring the critical load to the reserve power system.
 14. Themethod of claim 13 wherein determining if the reserve power system cansupport the critical load comprises: calculating the total load of thereserve power system; determining that the reserve power system cansupport the critical load if the total load is below a pre-determinedreserve threshold; and determining that the reserve power system cannotsupport the critical load if the total load is equal to or above apre-determined reserve threshold;
 15. The method of claim 14 whereincalculating the total load of the reserve power system comprisescalculating the load of a reserve UPS.
 16. The method of claim 13wherein determining if the reserve power system can support the criticalload comprises determining whether the reserve power system is in abypass mode.
 17. The method of claim 13 further comprising: receiving aglobal inhibit signal from the reserve power system; monitoring theavailability of the primary power source; and transferring the criticalload to the primary power source as a step load upon determining thatprimary power source is available.
 18. The method of claim 11 furthercomprising: monitoring a primary power source after transferring thecritical load to the reserve power system; and transferring the criticalload to the primary power source upon determining that primary powersource is available.
 19. The method of claim 11 further comprisingtransferring the load of the reserve power system to a secondary reservepower system via an automatic bypass input of a reserve UPS within thereserve power system.
 20. The method of claim 11 further comprising:initiating a time delay engine start timer in response to detecting anoutage of the utility; and issuing a start generator command in responseto determining that the time delay engine start timer has expired.